ath9k_hw: fix division by zero in the ANI monitor code

The commit "ath9k_hw: remove code duplication in phy error counter handling"
split off some duplicate code into a separate function, but did not have a
return code for aborting ANI processing based on counter values.
This introduced a divide by zero issue.
This patch adds the missing return code check in ath9k_hw_ani_monitor

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 7 insertions, 6 deletions

diff --git a/drivers/net/wireless/ath/ath9k/ani.c b/drivers/net/wireless/ath/ath9k/ani.c
index 3aa8fb1ad77f..9297f574b71c 100644
--- a/drivers/net/wireless/ath/ath9k/ani.c
+++ b/drivers/net/wireless/ath/ath9k/ani.c
@@ -633,7 +633,7 @@ void ath9k_ani_reset(struct ath_hw *ah, bool is_scanning)
         REGWRITE_BUFFER_FLUSH(ah);
 }
 
-static void ath9k_hw_ani_read_counters(struct ath_hw *ah)
+static bool ath9k_hw_ani_read_counters(struct ath_hw *ah)
 {
         struct ath_common *common = ath9k_hw_common(ah);
         struct ar5416AniState *aniState = &ah->curchan->ani;
@@ -646,10 +646,10 @@ static void ath9k_hw_ani_read_counters(struct ath_hw *ah)
         ath_hw_cycle_counters_update(common);
         listenTime = ath_hw_get_listen_time(common);
 
-        if (listenTime < 0) {
+        if (listenTime <= 0) {
                 ah->stats.ast_ani_lneg++;
                 ath9k_ani_restart(ah);
-                return;
+                return false;
         }
 
         if (!use_new_ani(ah)) {
@@ -683,7 +683,7 @@ static void ath9k_hw_ani_read_counters(struct ath_hw *ah)
                         REG_WRITE(ah, AR_PHY_ERR_MASK_2,
                                   AR_PHY_ERR_CCK_TIMING);
                 }
-                return;
+                return false;
         }
 
         ofdmPhyErrCnt = phyCnt1 - ofdm_base;
@@ -695,7 +695,7 @@ static void ath9k_hw_ani_read_counters(struct ath_hw *ah)
         ah->stats.ast_ani_cckerrs +=
                 cckPhyErrCnt - aniState->cckPhyErrCount;
         aniState->cckPhyErrCount = cckPhyErrCnt;
-
+        return true;
 }
 
 void ath9k_hw_ani_monitor(struct ath_hw *ah, struct ath9k_channel *chan)
@@ -711,7 +711,8 @@ void ath9k_hw_ani_monitor(struct ath_hw *ah, struct ath9k_channel *chan)
         if (WARN_ON(!aniState))
                 return;
 
-        ath9k_hw_ani_read_counters(ah);
+        if (!ath9k_hw_ani_read_counters(ah))
+                return;
 
         ofdmPhyErrRate = aniState->ofdmPhyErrCount * 1000 /
                          aniState->listenTime;